Photogrammetric evaluation of corrective surgery for trigonocephaly

An in-vivo study on the effect of head orientation in the measurement of anthropometric points in stereophotogrammetry

BACKGROUND

It is well known that in bidimensional photography the orientation of the head is fundamental to obtain a correct reproduction of the subject. Even minimal errors in yaw, roll and pitch of the head can be cause of unreliability of the photography itself. This is not the case in three-dimensional photography in which head positioning may have no influence on the reliability of the results since on the computer the 3D reconstruction of the face can be oriented as desired, allowing any small errors to be corrected. The authors, in a previous in-vitro study, demonstrated this using a mannequin of the head. In the present study, the Authors repeat the study in vivo to verify any differences.

METHODS

Seventeen anthropometric points were marked on the face of a young adult female (26 years old) with eyeliner. Images of the face were then acquired with a stereo-photogrammetric system (Face Shape 3D MaxiLine) in natural head position and with varying degrees of roll, pitch and yaw. The anthropometric points marked on the skin were then recognized and marked on a digital software (Viewbox, dHAL Software, 6 Menandrou Street, Kifissia 14561, Greece) on each individual image. 14 linear distances between these points were measured using the same software.

RESULTS

The linear distances of these points in the stereophotos taken at centered positions were then compared with those taken with different degrees of roll, pitch and yaw. This study confirms previous results obtained in vitro regarding the presence of areas of non-equivalence (P<0.05) when comparing the frontal and lateral regions of the face at various angles.

CONCLUSIONS

However, it introduces important suggestions on the collection of data from specific anthropometric points. If these points are to be assessed, the medical staff will have to take special precautions to obtain reliable images.

3D Analysis of the Cranial and Facial Shape in Craniosynostosis Patients: A Systematic Review

With increasing interest in 3D photogrammetry, diverse methods have been developed for craniofacial shape analysis in craniosynostosis patients. This review provides an overview of these methods and offers recommendations for future studies. A systematic literature search was used to identify publications on 3D photogrammetry analyses in craniosynostosis patients until August 2023. Inclusion criteria were original research reporting on 3D photogrammetry analyses in patients with craniosynostosis and written in English. Sixty-three publications that had reproducible methods for measuring cranial, forehead, or facial shape were included in the systematic review. Cranial shape changes were commonly assessed using heat maps and curvature analyses. Publications assessing the forehead utilized volumetric measurements, angles, ratios, and mirroring techniques. Mirroring techniques were frequently used to determine facial asymmetry. Although 3D photogrammetry shows promise, methods vary widely between standardized and less conventional measurements. A standardized protocol for the selection and documentation of landmarks, planes, and measurements across the cranium, forehead, and face is essential for consistent clinical and research applications.

A Suture-specific Photo Score for Metopic Synostosis

Head shape assessments in children with metopic synostosis are a relevant outcome measure in addition to functional measures, such as neurocognitive outcomes, behavioral outcomes, and visual functioning outcomes. However, consensus on head shape assessments in children with metopic synostosis is lacking. The aim of this study is to develop a reproducible and reliable suture-specific photo score that can be used for cross-center comparison of phenotypical severity of metopic synostosis and evaluation of esthetic outcome of treatment later in childhood. We conducted a retrospective study among nonsyndromic metopic synostosis patients aged <18 years. Preoperative and postoperative photosets of patients with metopic synostosis from 6 expert centers were included. The photo score was discussed in the group of expert craniofacial plastic surgeons and pediatric neurosurgeons. Interrater reliability was determined with modified weighted Fleiss' kappa and intraclass correlation coefficients. Correlation between individual photo score items with overall phenotype was assessed using Spearman correlation analyses. The metopic synostosis photo score contained the following items: "wedging of the forehead", "hypotelorism", "temporal hollowing", "biparietal widening,"and an assessment of "overall phenotype". Items were scored on a 4-point ordinal scale ranging from normal to severe. We found moderate interrater reliability for all items, but substantial agreement for the summed scores. Correlation with overall phenotype was lowest for biparietal widening. To conclude, although agreement on individual photo score items was suboptimal, the agreement on the summed score was substantial, which indicates there is consensus on the overall severity of the metopic synostosis phenotype.

The Use of Artificial Intelligence for the Classification of Craniofacial Deformities

Positional cranial deformities are a common finding in toddlers, yet differentiation from craniosynostosis can be challenging. The aim of this study was to train convolutional neural networks (CNNs) to classify craniofacial deformities based on 2D images generated using photogrammetry as a radiation-free imaging technique. A total of 487 patients with photogrammetry scans were included in this retrospective cohort study: children with craniosynostosis (n = 227), positional deformities (n = 206), and healthy children (n = 54). Three two-dimensional images were extracted from each photogrammetry scan. The datasets were divided into training, validation, and test sets. During the training, fine-tuned ResNet-152s were utilized. The performance was quantified using tenfold cross-validation. For the detection of craniosynostosis, sensitivity was at 0.94 with a specificity of 0.85. Regarding the differentiation of the five existing classes (trigonocephaly, scaphocephaly, positional plagiocephaly left, positional plagiocephaly right, and healthy), sensitivity ranged from 0.45 (positional plagiocephaly left) to 0.95 (scaphocephaly) and specificity ranged from 0.87 (positional plagiocephaly right) to 0.97 (scaphocephaly). We present a CNN-based approach to classify craniofacial deformities on two-dimensional images with promising results. A larger dataset would be required to identify rarer forms of craniosynostosis as well. The chosen 2D approach enables future applications for digital cameras or smartphones.

Infants With Trigonocephaly Treated With Fronto-Orbital Remodelling and Endocortical Positioning of Resorbable Plates-A Retrospective Cohort Study Including 101 Patients

PURPOSE

Fronto-orbital remodeling is the gold standard for surgical treatment of metopic synostosis in many craniofacial centers. For fixation, resorbable materials are widely used. Because of swelling during resorption, the positioning of the plates can be relevant. Therefore, the goal of this study was to investigate whether there are limitations to endocortical positioning of resorbable plates.

METHODS

In this retrospective study, all patients with metopic craniosynostosis resulting in trigonocephaly, who were treated with a standardized fronto-orbital remodeling and endocortical positioning of resorbable plates, between February 2012 and December 2019 were included. The endpoint of this study was the postoperative complications that can be attributed to the material used.

RESULTS

A total of 101 patients, who were treated at our unit, could be included with a male predominance, 81 (80.2%) boys versus 20 (19.8%) girls. Surgery was performed at a median age of 9 months (±2.56). No complications were seen related to resorbable plates. All patients of our study population were categorized as Whitaker classification I and II.

CONCLUSION

This study shows that the risk level in using endocortical resorbable plates positioned on the inner surface of the bone is low. From an aesthetic point of view, we could not detect any disadvantage.